The present invention relates to a path quality control technology in a network system comprising a plurality of networks.
For a network to transmit content requiring a real time capability, such as voice and video, while guaranteeing its real time capability, the network needs to perform a quality of service (QoS) control that allocates a bandwidth to each path on the network. Such a QoS control is known to be performed on an end-to-end basis according to the kind of traffic without causing any conflict in the entire network by using a policy server that manages quality control settings of network equipment in an integrated manner at one location. Such a policy server makes a quality control setting on each network equipment according to a described policy. Therefore, simply describing the policy of network operation, management and others in the policy server allows the network administrator to perform the QoS control, which gives priority to transmitting content requiring a real time capability, such as voice and video, assigning an absolute bandwidth, and processing important business applications, such as enterprise resource planning (ERP) and e-business applications.
At present, to realize this quality control using the policy server that does not rely on the network equipment vendors, the Internet Engineering Task Force (IETF), a standardization organization, is developing standards for the policy framework.
The policy server is capable of managing at one location in an integrated manner the quality controls of individual paths on the network but within a range of the network managed by that policy server. Hence, in a network system consisting of a plurality of networks each with its own policy server, the policy server-based QoS control cannot be performed on a path that extends over two or more networks. Nor is it possible to perform the QoS control in a way that does not violate the policies of the policy servers residing in the networks through which this path passes. If, however, an additional policy server that centrally manages the whole network system made up of a plurality of networks is provided, the QoS control may be applied also to the path extending to a plurality of networks in a way that conforms to a predetermined policy. Where the network system is large or its architecture is subject to frequent changes, the cost of installing and operating a policy server that performs such a non-distributed management will be enormous.
It is an object of the present invention to provide a network system which has a plurality of networks each having a policy server and which performs by using the policy server of each network the QoS control on a communication extending to two or more different networks.
To achieve the above objective, the present invention provides a network system which has a plurality of interconnected networks each having a policy server, the policy server setting a quality-guaranteed path in the network according to a policy held in the policy server, the policy server comprising:
a policy holding means to hold a policy defining a quality that can be guaranteed in its own network, or local network, for an inter-network communication;
a policy publicizing means to make public the policy held in the policy holding means to the policy servers of other networks;
a guaranteed quality calculation means to calculate, from a policy publicized by a policy server of a network on a path between the local network and other network, a quality that can be guaranteed for the path between the local network and the other network; and
a quality-guaranteed path setting means to provide a quality-guaranteed path, the quality-guaranteed path having a guaranteed quality within the quality calculated by the guaranteed quality calculation means for the path between the local network and the other network.
This network system can provide a quality-guaranteed path extending to a plurality of networks which has a quality guaranteed by, and not violating, the policies made public by the policy servers of a plurality of networks associated with the quality-guaranteed path to be provided. Therefore, in a network system having a plurality of networks each having a policy server, the QoS control can be performed on a communication extending to a plurality of networks by using the policy servers of the networks.